We were promised it was temporary.
Yes, when Satoshi put in the limit, he also reassured us on its temporary nature by describing the mechanism to change it (by adding a higher block size starting at a far future block so that there would be adequate time for upgrades and get us past the HARD fork issue.). ...I have my own ideas on the best ways to do that. Somewhat better than Gavin's proposal, and only a little more complicated.
Its not something we've done though. So when folks say things like "no problem if 2SHA-2 256 is cracked by quantum, we'll just change the algorithm", I cringe when I hear that word "just". It doesn't belong, it is not a minor change and it doesn't make sense to minimize the impact and challenge.
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In some ways, a SOFT fork such as SCs present similar challenges. In some ways it is easier but in others it is harder. Compatible and non-compatible software/hardware can run at the same time and on the same chain. The security profile gets a little complicated there. A MM'd SC can be mined by equipment that can't process an SPV (and so would accept any attempt as valid).
The economic impact is also easy to underestimate, and assumptions about things for which we have no evidence and only untested theory are simply insane.
Look at the number of times the word "will" is used to make some untested theory sound like it is a proven fact. Doing so is likely to make any scientist (or engineer) cringe with contempt for the author. It is something I struggle with, because although I agree with the notion of exploring the innovation of SC, and working toward adding it to the Bitcoin tool belt of possible solutions for certain problems... We kill that possibility by making unsupportable claims about an uncertain future. It is so easy to do bad marketing in this space because just about ALL the real "customers" are so much smarter and more knowledgeable than the marketing folks on what they are pushing. Everyone sees when the conclusions are assumed in the argument, most are just too polite to say much about it.
The marketing folks should consider their audience when posting here.
It doesn't make sense to minimize the impact and challenge.